NiuNiu MaTe

Feb 15, 2022 · Fundamentals

Why Do Only Perfect Squares Stay Lit? Solving the Bulb Switch Puzzle

The article explains the classic bulb‑switch problem, showing how toggling bulbs in successive rounds leads to only those positioned at perfect‑square indices remaining on, derives the mathematical reasoning behind the pattern, and presents a concise O(1) solution using the integer square‑root of n.